The revised National Planning Policy Framework and its implications for FRAs and SFRAs

The revised National Planning Policy Framework (NPPF) was released on 24 July 2018. So what impact will this have on how flood risk is assessed for planning, both strategically at a Local Planning Authority scale (LPA) through Strategic Flood Risk Assessments (SFRA) and in more detail at a site scale as part of Flood Risk Assessments (FRA)?

General Observations

The new guidance mostly involves a change in emphasis with respect to the considerations that are given to flood risk, primarily with respect to climate change and resilience. The most significant introductions for evidence not previously required are:

The requirement to identify policies and physical measures to provide for resilience to climate change effects.

The consideration of cumulative impacts in, or affecting, local areas susceptible to flooding.

The specific requirement for sustainable drainage systems and the need to evidence their use in FRAs.

The requirement to prepare emergency plans in FRAs.

The sequential approach and ‘flood risk from all sources’

Updated wording suggests that the fundamental premise of the sequential approach to avoiding inappropriate development in areas of high flood risk (by applying the Sequential and Exception Tests) will remain in place.

The requirement to ‘manage flood risk from all sources’ (para 156) is also unchanged. While the sequential approach can in theory be applied to other sources, the level of detail and certainty of risk data and mapping varies for difference sources, and areas at risk often interact or overlap.

Cumulative impacts

New Houses – Upton SuDS

New to the updated NPPF is the requirement that strategic policies should also now consider the ‘cumulative impacts in, or affecting, local areas susceptible to flooding’ (para 156).

Previous policies have relied on the assumption that if each individual development does not increase the risk of flooding, the cumulative impact will also be minimal. However, if there is a lot of development occurring within one catchment, particularly where there is flood risk to existing properties or where there are few opportunities for mitigation, the cumulative impact may be to change the flood response of the catchment.

The risk of this could be identified at a high level, by comparing potential development site locations with hydrological catchments and areas of existing and historic risk to people and property. These will be the locations where existing communities will be most alarmed at the prospect of further development exacerbating existing problems. Detailed conclusions on cumulative effect however would require certainty on which sites would be likely to be allocated, the size/density of the development, and potentially hydraulic modelling to test impacts downstream.

Climate change and future flood risk

SFRAs diagram to explain Flood Zones

There has been a strengthening of wording on future risk under climate change, in that the ‘sequential approach should be used in areas known to be at risk now or in the future from any form of flooding’ (para 158).

It is not uncommon that the modelled Flood Zone 3a plus climate change estimate is more extensive than present day Flood Zone 2, i.e. falls within Flood Zone 1, and these sites had the potential to fall through the cracks of the Sequential Test in the past.

We have long recommended that SFRAs include screening sites for future risk at a Level 1 stage and have highlighted this future risk to LPAs to include in their Sequential Test for some time now (most SFRAs prepared by JBA have included this evidence).

Natural flood management

There has been an additional reference to the use of Natural Flood Management (NFM) techniques to reduce the causes and impacts of flooding (para 157c).

At site level, NFM measures can potentially be incorporated within a site and there is an overlap with Sustainable Drainage Systems (SuDS), but influencing NFM at a catchment scale draining to the site may be more difficult.

Sustainable Drainage Systems

SuDS – Development site underwater

The requirement for SuDS has been strengthened, both in para 163c and also given a full paragraph (para 165) outlining the requirement to:

Take advice from the Lead Local Flood Authority (LLFA)

Have appropriate proposed minimum operational standards

Have maintenance arrangements in place

Where possible provide multifunctional benefits.

This is a very welcome addition to planning policy, in the absence of the enactment of Schedule 3 of the Flood and Water Management Act (2010). However, it only applies to major developments and so potentially does not capture circumstances where there ‘is clear evidence that this would be inappropriate’. It is possible that clarity on what evidence is required is subsequently set out in the Planning Policy Guidance (PPG), and that these circumstances would be exceptional.

We would observe that all developments (major and minor) can include SuDS, providing multiple benefits contributing to many of the other NPPF policies – climate change, healthy and safe communities, well-designed places, conserving and enhancing the natural and historic environment.

Where site conditions are more challenging the type of SuDS may need to be adapted to the site’s opportunities and constraints and used in combination with traditional techniques if absolutely necessary.

At a strategic level, this means identifying SuDS opportunities according to geology, soil type, topography, groundwater conditions etc, their potential impact on landtake, and setting out local SuDS guidance and opportunities for adoption and maintenance.

At flood risk assessment/drainage strategy level this means early engagement with the LLFA and the client to set expectations of what SuDS can be used on site, what impact this will have and how their multiple benefits will contribute to meeting other planning policy.

Emergency Plan preparation and agreement

This is considered to be a ‘catch up’ introduction to reflect practice that is already in place. There is a requirement that the plans are now agreed, and consideration will need to be given to the appropriate parties to this agreement. These will vary according to the specific circumstances and the nature of the risk and emergency that is being addressed.

Summary of the influential changes

Things that are different (most involve a change of emphasis)

(149) – There is potentially a requirement to provide further evidence on the infrastructure required to ensure future resilience of communities.

(150) – There is increased emphasis on the requirement to demonstrate that risks can be managed through adaptation measures, introducing the need to quantify the magnitude of the risks and the efficacy and practicality of measures that can be used to manage adverse effects.

(155) – There is greater emphasis in identifying development that avoids risks arising from climate change effects.

(156) – There is a requirement to consider cumulative impacts in, or affecting local areas susceptible to flooding.

(157[c]) – There is a requirement to consider the use of natural flood management techniques.

(162) – There is a greater emphasis on the requirement to consider the Exception Test when submitting FRAs for sites that have satisfied the Sequential Test – this is valid as the Exception Test assessment performed in a Level 2 SFRA can demonstrate that the principle of development can be supported, but when more detail is prepared in support of a specific application then further assessment is required.

(163) [b] and [c] – There is increased emphasis on FRAs including evidence on the need to consider flood resilience and resistance and sustainable drainage systems.

(163[e] – There is now specific reference to the need to prepare and submit an ‘agreed’ emergency plan.

(165) [a-d]– There is now specific inclusion of the requirements that should be included for sustainable Drainage systems

We have significant expertise in designing and installing flow gauging stations, including modifications of existing gauging stations to facilitate fish passage (e.g. through retrofitting of baffles or adding a Larinier fish pass in compound with an existing gauging weir). We can advise on siting, choice of method/feasibility and design. We have also excellent working relationship with NIVUS GmbH, with whom we have worked closely in designing new transit time ultrasonic stations.

Strategic studies and network reviews

We have an impressive track record in relation to delivering strategic hydrometric studies:

From January 2007 to September 2010, we carried out an extensive national review of the hydrometric network in England and Wales on behalf of the Environment Agency. The work was undertaken in two phases: i) River Gauging Network, ii) Rainfall Gauging Network. As well as a comprehensive review of the existing network and assessment of requirements to meet future initiatives, software tools for and guidance on network management were developed.[1]

From September 2008 to June 2010 we carried out a strategic review of Hydro-Meteorological Monitoring networks operated by the Office of Public Works in Ireland. This involved the identification of the long-term strategic needs for flood-related hydrometric and meteorological data in Ireland, including strategic management requirements for effective data collection and provision of flood related information.

In 2012 we carried out a detailed review of the Hydrometric Network in Yorkshire and North East, whilst involved a review of drivers of the flow and level gauging network, quantification of benefits derived from the network and outline of possible network improvements, specification of gaps and redundancy in existing network and prioritisation for network improvements based on operational requirements.

In 2015 we delivered a detailed review of the hydrometric network operated by the Environmental Protection Agency in Ireland. This included a detailed comparison of the hydrometric network in Ireland with those in Scotland, Wales and New Zealand.

We are currently (2018) helping Waterways Ireland to undertake an evaluation of their monitoring network.

All the data we collect and supply undergoes strict validation and data assurance processes before use/issue. We are also able to undertake independent validation or checks of third party data; a recent example being an independent review of the quality of hydrometric data collected by the Tweed Forum as part of their Eddleston Water Project.

Our team has been widely involved in defining procedures for data management and assessment of data quality, of which some of the higher-profile projects have included:

Development of Operational Instruction outlining how the HiFlows-UK flood peak database should be managed, and implementation of improvement measures including rating updates and evaluation (Environment Agency, 2014).

Reviews of the performance of the EA’s Tipping Bucket raingauge network, which included comparing accumulated rainfall from TBRs and their collocated storage raingauges and identifying reasons for any discrepancies in terms of calibration, site maintenance, under catch due to exposure, evaporation etc.

Development of a tipping bucket raingauge calibration procedure for the OPW.

Spot gauging service and rating curve development

We offer a spot gauging service using our own Valeport Model 801 Electromagnetic Open Channel Flow Meter, which we operate in accordance with BS EN ISO 748:2007 and which undergoes calibration every three years by the manufacturer. Recognising those situations where specialist equipment is needed we also have expertise with hired instrumentation including OTT’s QLiner, Sontek’s RiverSurveyor and FlowTracker devices and RD’s Stream Pro ADCP.

We have carried out flow gauging for Natural Resources Wales, Essex and Suffolk Water, National Trust and Irwell Rivers Trust, Aire Rivers Trust, South East Rivers Trust and the Environment Agency as well as private clients (e.g. in support of hydropower assessments, abstraction licence applications, internal drainage boards/water level management plans).

Our team is highly experienced in the development of new, and in the reviewing of existing Stage-Discharge and Velocity-Index ratings. We use our innovative in-house applications to aid hydrometric data review and analysis. To date we have derived over 100 new stage-discharge ratings on behalf of the Environment Agency. We also run training courses on the topic of extrapolation of high flow ratings and use of modelling to extend high flow rating limbs.

Training and support

We are expert trainers in hydrology (our team runs the foundation and advanced level training courses offered within the Environment Agency). We offer a range off-the-shelf courses covering theoretical and practical aspects of hydrological analysis but are equally able to provide tailored training based on real case studies and practical examples.

Experience of preparing 12 Water Cycle Studies since 2013, including several combined Water Cycle Study and Strategic Flood Risk Assessments

Open and easy to do business with, with a strong focus on innovation and customer service

We use a team of expert technical leads to provide oversight of the assessments of water infrastructure, water resources and water quality modelling

National coverage from 20 offices in the UK and Ireland.

Improving the management of water

Whilst the primary responsibility for delivering water and wastewater services lies with the water companies, Local Planning Authorities can use the planning system to promote solutions which contribute to improving the management of water and provide other benefits, including:

Sustainable Drainage Systems (SuDS) on new-builds and retrofit, including surface water disconnection for combined sewers to create capacity for development

Rainwater harvesting to reduce water demand in water-stressed areas.

Services we offer

Assess the present day and future capacity of the water resources, water supply, wastewater collection and treatment facilities

Identify how increase effluent discharges can be treated without causing detriment or preventing the receiving waster from achieving GES

identifying the responsibilities and timescales for implementing strategic infrastructure upgrades

Providing the evidence base for Local Plan policies on water efficiency, SuDS etc

Climate change analysis and adaptation.

Sustainability investigations

Investigation of impact of Habitats Directive and Water Framework sustainability reductions on water available for supply.

Aquator modelling to inform the impact of abstraction regimes on environmental indicators (e.g. lake water level, downstream river flow) and alternative water sources to support environmental impact assessments.

Assessment of the impact of sustainability reductions

Assessment and scenario modelling of water transfers (intra and intercompany).

Demand modelling and efficiency measures

Modelling of water demand under different scenarios including drought.

Quantification of the impact of drought measures on demand.

Drought planning and management

Development and review of drought triggers

Support for drought permit applications

Historic drought event characterisation

Drought frequency analysis and levels of service

Comparison of historic and extreme.

Climate change

Derivation of climate change inflow datasets for water resources models

Assessment of climate change impacts on available supply

Application of stochastic methods for climate change modelling.

Water resources modelling

Aquator model build and development

Application of Hysim, Mike BASIN, WRAPsim and iThink models

Deployable output assessment for water resource management plans

Investigating the deployable output benefits and utilisation of new sources.

Many development consents have archaeology and heritage related planning conditions. We have the expertise to specify mitigation measures and obtain local authority agreement to the proposals. We have experience of specifying watching briefs, strip, map and sample and open area excavations. We can also help you procure and manage specialist sub-contractors to implement the mitigation.

Evaluation and Survey

In line with the requirements of NPPF many development sites require pre-submission or pre-determination heritage surveys. We have extensive experience of negotiating with LPA Archaeological Advisers, specifying and designing evaluation surveys such as geophysical survey, evaluation excavation (trial trenching), LiDAR analysis and building surveys.

Conservation Management Planning and Heritage Partnership Agreements

Identifying measures for the long term management and development of heritage assets within a property portfolio can significantly reduce the amount of time spent negotiating consents and identifying heritage work specifications. They provide a framework within which long term sustainable management of the historic environment can be implemented.

Design Advice

The historic environment contributes to a sense of place. There are many opportunities for new developments to harness the historic environment to give a sense of identity and place to new developments and link them to the surrounding landscapes. We can provide advice at an early stage of the design process to enable these opportunities to be recognised and incorporated adding value to the development design.

Historic Landscapes and Assessment of Setting

The wider setting and context of heritage assets is a key consideration within the determination of many planning applications, particularly those for infrastructure projects or development within or close to sensitive areas such as World Heritage Sites and Conservation Areas.

We have extensive experience of defining the setting and contribution this makes to the significance of heritage assets and assessing the effects of development on these settings.

These encompass the whole of the historic environment. They are designed to meet the requirements of NPPF and provide comprehensive assessment to meet the clients’ needs and reduce project risks from the outset.

Marc wanted to be part of an organisation with a strong set of values – more than words, one that supports and advances science and understanding to develop its staff and our wider professional community.